The present invention involves a process of coating a wet, non-woven fiber glass mat with foam or froth on the same wet process line used to make the mat, as an intermediate step in the mat manufacturing process, and the coated fiber glass mat products that result. These coated mats have many uses, but are especially useful as a facing on a gypsum wallboard for exterior application and on which stucco is applied.
Fibrous non-woven mats are often formed into a wet mat from an aqueous dispersion of fibers such as glass and/or synthetic organic fibers can include other fibers such as cellulose fibers, ceramic fibers, etc. and can also include particles of inorganic material and/or plastics. Usually a solution of urea formaldehyde resin, usually modified with a thermoplastic polymer, or one of many other known resin binders is applied to a the wet non-woven web of fibers and then, after removing excess binder and water, the bindered web is dried and heated further to cure the urea formaldehyde resin or other resin binder to form a non-woven mat product. A typical process is disclosed in U.S. Pat. Nos. 4,112,174 and 3,766,003, the disclosures of which are hereby incorporated herein by reference.
The fiberglass mat (Johns Manville's 7502 Mat—99 gms/square meter) made using a binder of modified urea formaldehyde resin performed good in the process disclosed in U.S. Pat. No. 4,647,496 to make a faced insulating gypsum board, also disclosed in that patent, but the mat was not as strong as desired which caused process breakouts adding to production costs. This mat was also more rigid than desired Which made it difficult to fold around the edges of the board and also irritated the hands and arms of the workers handling and installing the insulating board product. Further, when the faced insulated gypsum board was cut, the dust from the mat was excessive and further irritated those it contacted, particularly if the workers bare arms, etc. were sweaty and exposed to the dust. Skin abrasion and irritation was also a problem for those handling the mat and the faced board when not wearing gloves and long sleeve shirts.
To address the inadequate strength problem a small portion of polyester, polyethylene terathalate (PET), fibers were used in place of an equal amount of glass fibers and the urea formaldehyde resin binder was replaced with an acrylic binder containing a small amount of a stearylated melamine. This improved the strength adequately and also improved the handling characteristics of the mat somewhat, i. e. the mat is friendlier to those handling and installing the mat or board, but the acrylic bound mat is more expensive and less fire (flame) resistant. Such mats are disclosed in U.S. Pat. No. 5,772,846. While the mats disclosed by this latter reference have substantially improved “hand” and cause very little abrasion or discomfort in handling, the cost is higher, the mat is less flame resistant than the mat disclosed in U.S. Pat. No. 4,647,496 and further improvement is still desired by some users.
There still exists a need for a nonwoven fiberglass mat that has better flame resistance, lower cost and good handlability (flexible and non abrasive/non irritating to the skin).